My 3D object looks different when exporting it to Unity?
It sort of looks like you have a subsurf modifier on the object. Unity doesn't actually take the raw blender file when you import it as an asset. It actually exports the blender model as an fbx and then imports that into Unity. Exporters tend to apply modifiers before they export. What Unity is allowing you to do is sit back while it does all of the export/import work for you. It's also going to have some wonkiness when it comes to translating the materials so you should always use a UV texture even if you're just talking about a flat color on the object just so you have some predictability and control.